Method of mining coal.



H. A. KUHN.

METHOD OF mmme COAL.

. APPLICATION FILED run/1s. 1914.. 1,237,063. PatentedAug. 14,1917.

ETS'SHEE1' I \k I NI-messes. NR \NVENTOR I 7 v m ma HARRY A. KUHN, OFPITTSBURGH, PENNSYLVANIA.

METHOD OF MINING COAL.

Specification of Letters Patent.

Patented Aug. 14, 191'7.

Application filed May 18, 1914. Serial No. 839,330.

scri tion thereof. 1M?

y invention relates to method of mining coal.

The object of my invention is to provide a method of disrupting orbreaking up a mass of coal in its original bed by the use of explosives,the operation being carried on in such a way that thecoal iswnot blownto small bits or atoms, so torn and disrupted by the explosiofl'as to rduce" a powder or slack coal, but in which the coal'is'split along itsnatural lines of cleavage, and then further separated, so that the solidwall of coal is broken up intolumps of large size which may be readilyremoved by a suitable digging and conveying apparatus, or even may beremoved by a pick and loaded by hand upon the pit cars in the mannermost commonly employed.

To these ends my invention consists, generally stated, in making a kerfin the solid wall of coal and inserting explosive material into thiskerf, drilling into the solid wall removed from the kerf in the usualway, shooting this coal so that the coal is separated along its lines ofcleavage and settles into said kerf, and finally setting off the firstcharge inserted in the undercut, whereby the coal is further disruptedand separated, the force last applied being preferably directedupwardly, or outwardly, so as to give the desired effect of separatingthe coal into lumps, so that it may be readily dislodge-d and carriedaway.

In the accompanying drawings, Figure 1 is a view of a body of coal underwhich an I undercut has been made and the explosive inserted in theundercut; Fig. 2 is a like view showing the wall of coal after the firstshooting operation; Fig. 3 is a like view after the second shootingoperation; Fig. 4

is an enlarged detail of the form of torpedo employed by my process, andFig. 5 is a face view of coal showing the torpedo in position in theundercut and the hole drilled for the insertion of the explosive tocause the first shooting of the coal.

In carrying out my improved method the wall of coal 2 which is to bemined, is first undercut as at 3, this undercutting being done by anysuitable kerf cutting machine. After the undercut has been made, thetorpedo or other explosive device 4 is inserted in the undercut. Thistorpedo comprises the lower cupped portion 5 which contains a suitableexplosive 6 and covering the cup 5 1s the cap or cover 7 which fitsloosely over the cup 5 and leaves a space 8 between the 1nside of thecap and the outside of the cup for the passage of the wires 9. The upperedge of the cup is also provided with the opening 10 through which thewires pass into the cup, and the wires are connected with thepercussion-cap 11. In the drawin I have illustrated these torpedoes asroun in shape, and, as shown in Fig. 5, they are arranged at intervalsin the rear of the undercut, and in order to get the full effect of theaction of the torpedoes I connect each pair with a plate 12 which actsto distribute the effect of the explosion along practically the entirewidth of the undercut, as will more fully hereinafter appear.

After the torpedoes have been inserted in this manner within theundercut, the holes 13 are drilled in the wall of coal at a suitableheight preferably extending slightly upwardly as indicated in Fig. 1 andwhen said holes have been drilled, they are charged with powder or othersuitable explosives.

With these preliminary preparations, the charge of powder in the holes13 is set off and this charge is of such strength as to separate thecoal along its lines of cleavage without breaking it up into smallparticles, the coal after this first explosion settling down tosubstantially the position indicated in Fig. 2, thereby filling up theoriginal undercut 3. The torpedoes 4 are then set 011' and the wires 9extend off to a suitable point of safety, where by simply throwing aswitch, the circuit is completed and explosion of the torpedoes 4. takesplace. As the torpedoes are inclosed by the mass of coal on all sides,and as the tops or covers 8 are movable, the line of least resistance isupwardly and accordingly an upward force is applied which beingdistributed by the plates 12 across the out, acts to disrupt the mass ofcoal further and separate the coal into large lumps in substantially themanner indicated in Fig. 3.

In case there are any bands of slate 15, such as indicated in Fig. 5,and these bands of slate are not broken up by the first explosion, thesecond explosion will act to break up said bands and s0 prevent thebridging of the coal above the same, and the difliculty of its removalby the machine.

With the coal in this condition, the removal of it can be accomplishedin any suitable manner, but I prefer to employ the mining machine, suchas shown and described in an application filed of even date herewith,Serial No. 839,326, and a portion of which is indicated in Fig. 3. Thismachine is adapted to advance along the original floor of the mine andthe undercut, and digging under the coal which has been acted on in theabove manner, the coal is moved onto the conveyer and by the conveyormoved back to the pit car in the rear. By simply separating the coalalong its lines of cleavage by the first shooting operation and byfollowing that up by a disrupting force originating within the mass ofcoal first shot in this manner, the disrupting force in no case issufficient to disintegrate the coal into slack or pulverulent form butthe coal is left in large lumps which can be readily removed either bymachine or by hand, if so desired.

lVhat I claim is:

The method of mining coal consisting in forming a kerf in the wall ofcoal, insertingan explosive in said kert', shooting the wall of coal ata point removed from said kerf whereby the coal is separated along itslines of cleavage and settles into the kerf, and subsequently settingoff the explosive inserted within said kerf.

In testimony whereof, I the said HARRY A. KUIIN have hereunto set myhand.

HARRY A. KUHN. Witnesses:

JOHN F. WlLL, Ron'r. D. TOTTEN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

